the first stages of planet formation observed live

Around the young star AB Aurigae, a team of astronomers discovered, using ESO’s VLT, the signs of the birth of a planet and the precise place where it could form! Explanations from Anthony Boccaletti of the Paris Observatory, PSL University, who directed the study.

Surprisingly, the theory of planetary formation most accepted by the scientific community is a young and developing theory, so that each observation of a stage of the formation of planets is a means to refine this theoretical model.

A few months ago, observations made with theSphere instrument installed at Very Large Telescope (In 1993, ESO launched the VLT (Very Large Telescope) project and decided to install it on the Cerro Paranal site in the Chilean Andes, where the climate is particularly favorable for astronomical observations. It … “data -image = “” data-url = “ / univers-vlt-2147 / “data-more =” Read more “>VLT) from the European Southern Observatory highlighted the telltale signs of a planetary system in formation around the young star AB Aurigae. This planetary system in formation, located at 520 light years of the Structure of the globe … “data-image =” “data-url =” https : // “data-more =” Read more “>Earth in the Set of small satellites … “data-url =” “data-more =” Read more “>constellation Auriga (the Coachman), is very well known to astronomers who have been observing it for almost twenty years.

These observations made it possible to identify a “ prominent spiral structure with a “torsion“Which marks the site” where a planet could form Explains Anthony Boccaletti of the Paris Observatory, PSL University (France), who directed the study. Thistorsion is predicted according to certain theoretical models of planetary formation , says co-author Anne Dutrey of the Laboratoire d ‘astrophysics from Bordeaux (LAB). It corresponds to the ” connection of two spirals – one winding towards the inside of the orbit in astronomy
In astronomy, the orbit indicates the closed trajectory followed by a celestial body around another celestial body in a periodic manner, under the influence of … “data-image =” https: //cdn.futura-sciences .com / buildsv6 / images / midioriginal / 9/2 / e / 92eefd02ac_49145_iss-terre-soleil-nasa-s-marshall-space-flight-center-flickr-cc-nc-20.jpg “data-url =” https: // “data-more =” Read more “>orbit of the planet, the other extending outward – which meet at the location of the planet
They allow the gas and to the dust of the disc of to accrete on the planet in formation and to make it grow “, specifies the researcher.

This observed structure could be the ” first direct evidence of the birth of a planet “, Emphasizes Anthony Boccaletti. This point of ” disturbance is about the same distance from the star as Neptune from the Sun “, He adds.

When and where planets are formed

These observations also provide crucial clues to help scientists better understand this process. ” We have to observe very young systems to really capture the moment when the planets are formed says Anthony Boccaletti. But, until now, astronomers have failed to take sufficiently sharp and deep images of these young discs to find the ” specific point that indicates where a baby planet should be born ” This is today done !

These new images, ” acquired by the instrument Sphere and which are the most precise and deepest of the AB Aurigae system obtained to date “Show a” amazing spiral of dust and gas around AB Aurigae ” Now, spirals of this type signal the presence of baby planets which “excite” the gas, creating ” disruption in the wave-like disc much like the wake of a boat on a lake “Explains Emmanuel Di Folco, also from LAB who also participated in the study. As the planet revolves around the central star, this ” wave takes the form of a spiral arm “And the area in very bright yellow near the center of AB Aurigae is” one of those disruption sites where the team thinks a planet is forming », Specifies Emmanuel Di Folco.

Let’s give the floor to Anthony Boccaletti:

Do you have an idea of ​​the size of the planet in formation or is it currently a proto-planet?

Anthony Boccaletti : No, not specifically. We see the shape of the spiral and we deduce that it fits rather well with the models which consider these spirals as produced by planets. But, precisely, the model is very simple and does not really depend on the unit of mass: the kilogram
The mass is represented by the symbol m and, in … “data-image =” “data- url = “” data-more = “Read more”>mass of the planet. In the article, we try to make estimates by supposing that the planet is surrounded by a circumplanetary disc and that this disc emits light in infrared. This implies a model that links the rate ofaccretion of this disc with its brightness. We find that an object of a few masses of Jupiter could explain the observed flow.

A future giant planet fizzy then?

Anthony Boccaletti : Yes. It would rather be a massive planet to produce such spirals so evident in the images.

Concretely, what do we see of the planet in these images?

Anthony Boccaletti : We especially see the spiral. The planet is probably buried in gas and dust and is not visible. Which is a bit in contradiction with what I said above about the estimation of its mass assuming that the measured flux comes from a circumplanetary disc.

What does this discovery teach us about the formation of planets?

Anthony Boccaletti : We know discs with spirals, we know planets imaged inside discs (Beta Pic b, PDS70 b, also observed with Sphere), but we have never been able to highlight a connection between the two! Precisely because, when there is a spiral, it is because the quantity of gas is still too high to allow observations in optics to reveal the planet. Here, we begin to see for the first time a structure in the spiral which corresponds to what we expect if this spiral is generated by a proto-planet. Still not a direct link but we’re getting a little closer.

Are further observations planned with instruments in service or is it necessary to wait for future instruments, such as those on board the JWST, to improve Sphere’s observations?

Anthony Boccaletti : What will not change is the ability of our instruments to “cross” gas. This one will still be there for … a few thousand or millions of years! But yes, other observations are planned. First with Sphere, to measure if this structure is moving. We can already guess a displacement between the images of Alma and those of Sphere, but confirming it and obtaining a Keplerian orbit would be proof that it is indeed a massive object, planet type, which follows the Kepler’s laws. Then we also asked VLT for observations with Muse to find out if there is accretion. This would show that a circumplanetary disk (and therefore a planet) exists.

It will also be necessary to increase the resolution angular on this object?

Anthony Boccaletti : Effectively. This will be necessary to resolve these Ces even better … “data-url =” “data-more =” Read more “>torsion of the spiral and compare with more complicated models, called hydrodynamics. This will be possible withExtremely Large Telescope of the’ESO, being construction. We should be able to see directly and more precisely how the gas dynamics contribute to the formation of planets. The James Webb Space Telescope (JWST), whose launch is planned for March 2021, could be used to measure the flux of the object in mid infrared, especially if there is a circumplanetary disk because its flux will be higher at 10 microns only 1 or 2 microns.

AB Aurigae: the formation of a live planet?

Article by Laurent Sacco published on 28/03/2008

A team of astronomers from the American Museum of Natural History has just used coronography, originally introduced in Theories established by physics apply in well defined frameworks.
Physics … “data-image =” “data-url =” https: // “data-more =” Read more “>physical solar, to observe the Recent studies tend to prove that brown dwarfs, even celestial objects even smaller and called “planemos”, are also surrounded by a protoplanetary disc. “data-url =” https: // news. “data-more =” Read the definition “>protoplanetary disc from the star AB Aurigae. They located an area where a planet would be forming right under our eyes.

The star AB Aurigae has attracted the attention of many astrophysicists for about ten years. It was observed by telescopes Hubble, Subaru and even with the There are several large architectures of interferometers.
Interferometers make it possible to create electromagnetic wave interference, as do … “data-image =” hanford-observatory-caltech-mit-ligo-lab.jpg “data-url =” “data-more =” Read more “>interferometer from the Plateau de Bure of the Institute for Millimeter Radioastronomy (Iram). Located about 470 light years away, this very young star, aged one to three million years, is of the Herbig Ae type and its mass is approximately twice that of The Sun is the closest star to the Earth, from which it is about 150 million kilometers apart. The Sun is located 8.5 kparsecs from the center of the Milky Way. In the classification of stars, the sun is a star of type G2.
The mass … “data-image =” “data-url =” https: // news. “data-more =” Read more “>Sun. She is surrounded by cocoon gas and dust and even has a protoplanetary disc. For several years, researchers believe that AB Aurigae is an ideal laboratory to show us how a thick disk of gas and dust becomes a thin disk much less rich in gas but in which planetesimals begin to form planets.

Figure 1. Click to enlarge. The protoplanetary disc of AB Aurigae observed by coronography in 2004 with Subaru. Note the spiral structure and the scale: the yellow bar at the bottom left of the right image indicates a distance corresponding to 1 second of arc, representing 144 Astronomical Units (1 AU is worth approximately 150 million kilometers).

Today, astrophysicist Ben R. Oppenheimer and his colleagues observe the disc of AB Aurigae using the same technique as that already used by the telescope Japanese Subaru atop Mauna Kea in Hawaii. It is a technique introduced in the early 1930s by the French astronomer Bernard Lyot, the coronography.

The basic idea is simple, consisting in making an instrument that allows observations to be made equivalent to those that can be made of the solar crown during a eclipse. The design of the instrument is not simple. It is indeed necessary to analyze finely the processes of diffraction and reflection caused by the introduction of a cover into a telescope to form an acceptable image. It also amounts, in the case of the Sun, to separate the light coming from the solar corona from that diffracted by the edge of the main objective. It is easy to understand that this technique can be used to observe a protoplanetary disc close to a star and originally drowned in the light thereof.

This is precisely the goal of astronomers engaged in the Lyot Project, like Ben R. Oppenheimer, who use the US telescope Air Force AEOS (Advanced Electro Optical System). Located atAir Force Maui Optical Station on the Study of volcanoes is volcanology or vulcanology. Volcanic activity is one of the … “data-image =” jpg “data-url =” “data-more =” Read more “>volcano Haleakala in Maui, AEOS is one of the most efficient adaptive optics systems in the world. His mirror deformable 3.63 meters in diameter is controlled by 941 cylinders controlled by computer and which constantly modify the form to correct the distortions of the images caused by In a … “data-url =” “data -more = “Read more”>turbulence atmospheric.

By taking a closer look at the latest images from AB Aurigae, researchers from Lyot Project discovered that there was an area depleted in gas and dust in the protoplanetary disc of the star as shown in Figure 2. Better, inside this area, the density of dust and gas increases again.

The simplest interpretation of these observations is that we are in the presence of a planet in formation accreting gas and dust and therefore cleaning around it. It could also be a brown dwarf, neither really a star nor quite a gas giant. To be sure of its nature, it would be necessary to determine the mass of the object and to verify that it indeed exceeds ten times the mass of Jupiter. Certain theoretical arguments, however, make the formation of a brown dwarf in a protoplanetary disk as Oppenheimer recalls, but it may be necessary to review the copy on this subject.

In the meantime, research continues and should not delay in providing us with new insights into the genesis process of our own solar system.

VIDEO” />This will also interest you

First image of a protoplanet captured by the VLT A protoplanet is forming around a young star, 370 light years from Earth. And, for the first time, the Sphere instrument, which equips the giant VLT telescope, in Chile, managed to provide images in July 2018. They show the planet digging a furrow in a cloud of gas and dust. Artist images, illustrating what its surface could be, have been added.

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